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    (Original post by Acrux)
    Un=k+(100-1)k
    =100k
    Not quite. You've correctly identified that a, the first term, = k, and the difference is k in the series, so Un = k + (n-1)k.

    You don't know what n is, but you know that Un, the final term (since there are n terms) is .... so ...
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    (Original post by Math12345)
    Careful.

    Count the bits in the brackets (1,2.....)
    Brackets is from 1- 100 which is 100 terms
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    (Original post by Acrux)
    Brackets is from 1- 100 which is 100 terms
    No it's from 1 to 100/k.

    So how many terms?
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    (Original post by SeanFM)
    Not quite. You've correctly identified that a, the first term, = k, and the difference is k in the series, so Un = k + (n-1)k.

    You don't know what n is, but you know that Un, the final term (since there are n terms) is .... so ...
    so 100=k+(n-1)k
    100=kn
    n=100/k

    so you cant assume there are 100 terms as it goes from k to 100?
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    (Original post by Acrux)
    so 100=k+(n-1)k
    100=kn
    n=100/k

    so you cant assume there are 100 terms as it goes from k to 100?
    Correct.
 
 
 
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